Milbemectin is composed of 30% milbemycin A3 and 70% milbemycin A4, exhibiting acaricidal and nematocidal properties effective against adult spider mites, their eggs, and C. elegans, with IC50 values of 5.3, 41.1, and 9.5 µg ml, respectively. It functions as an allosteric agonist of the Drosophila RDL GABA receptor, and demonstrates efficacy against the pinewood nematode, B. xylophilus, with an LC20 of 0.0781 mg liter.